Variation of Responses to Water Stress Between 'Tifton 85' and 'Tifway' or 'Coastal' Bermudagrass
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Field observations revealed greater retention of green leaf area and growth of 'Tifton 85' compared to common and 'Coastal' bermudagrass [Cynodon dactylon (L.) Pers.] under water stress. Our objective was to compare phenotypic and physiological responses to increased water stress between Tifton 85 and Coastal and between Tifton 85 and 'Tifway' bermudagrass under greenhouse conditions. Bermudagrass green leaf area, shoot and root dry weights, leaf CO 2 exchange rate (CER), H 2O exchange rate (WER), and conductance were measured under well-watered and reduced watering in two experiments. Tifton 85 retained greater green leaf area than Tifway under water stress in Exp. 1. The CER, WER, and conductance were less for Tifton 85 than Tifway, but water stress over 8 d reduced each variable for Tifway only. In Exp. 2, soil water content and green leaf area declined more for Tifton 85 than for Coastal bermudagrass over 14 d after watering ended. Greater root dry weight below the 13-cm depth indicated Tifton 85 depleted water content of the finite pot volumes more rapidly than Coastal under reduced watering. After 14 d without watering during Exp. 2, mean CER of green leaves was less than wellwatered pots for Tifton 85 but not for Coastal bermudagrass. Similar to phenotypic traits, leaf CER, WER, and conductance responses of Tifton 85 differed between experiments. These greenhouse experiments documented variation of responses to reduced soil water supply among bermudagrass and revealed the need to evaluate traits affecting water access and use for Tifton 85 and other bermudagrass under field conditions. Crop Science Society of America.